有关u-turn

小胡同

最近查google map for directions, 经常会看到需要u-turn。印象之中好像在主路上不可以，不管是否有不可u-turn的牌子。平常也看到有人在红绿灯处做u-turn。
请问u-turn到底是不是合法的？
7 N. c9 [# y$ g- j, G+ w谢谢！

EightBelow

U-turns
9 z* T$ a$ }5 r  a9 I( u• Do not make a U-turn unless you can do it safely and without interfering
with other traffic.
1 Y) `0 N. w3 x4 F• Outside urban areas U-turns are not permitted on a curve or near the
crest of a hill where the driver of another vehicle cannot see your vehicle.
$ M! L8 ^+ A- z# u5 `4 [U-turns are not permitted in urban areas in the following situations:
• On a roadway between intersections.
: j. l. e* _% r8 T• Where a sign prohibits making a U-turn.
2 m: ~, d* j3 W7 y+ t2 c, z8 H- d1 G• At an intersection controlled by a traffic-control signal (traffic lights).
• At an alley intersection.

无语

有红绿灯的地方U-Turn是违规的。